Generally, a Digital Rights agent (DRM) is technique to protect a rights object (RO) for digital contents and systematically manage it, and provides a protecting and managing scheme for preventing an illegal copy of the contents, obtaining the RO, creating/moving the contents, and consuming the RO and the contents. The DRM is applied to various applications such as a media player, an audio player, or an image viewer.
FIG. 1 is a configuration view showing a DRM system in accordance with the related art. As shown, the DRM system controls contents issued to a user by a content provider to be consumed only in a right-limit of RO. The content provider is an entity corresponding to a Contents Issuer (CI) or a Rights Issuer (RI).
The CI issues contents protected by a specific encryption method (hereinafter, will be referred to as DRM contents) so as to protect contents from a user having no access right, and the RI issues a Rights Object (RO) necessary to consume the DRM contents.
A DRM agent is mounted at a device thus to receive the DRM contents and ROs from the CI or the RI, and controls consumption of the DRM contents by analyzing a ‘License’ contained in the RO, and by converting the DRM contents to contents that can be consumed at a corresponding DRM Agent.
FIG. 2 is a block diagram showing a state that a Rights Object (RO) is moved between DRM Agents via an Right Issuer (RI).
Referring to FIG. 2, a first DRM Agent may consume an RO issued from an RI by a certain amount, and then transfer (move) the RO to a second DRM Agent via the RI. The first DRM Agent requests the RI to move the RO to the second DRM Agent, and transfers the RO to the RI (or deletes the RO). The RI responds to the request, and transfers the RO to the second DRM Agent by using an RO Acquisition protocol with the second DRM Agent.
FIG. 3 is a schematic block diagram showing a state that an RO and a DRM content that can be user by a DRM Agent is imported to the DRM Agent via a Local Rights Manager (LRM).
Referring to FIG. 3, a DRM content and an RO (or license) that have been protected by an external DRM System, may be imported (changed) that can be used by a DRM Agent, via a Local Rights Manager (LRM). The reason is because a DRM content and an RO having been received from an external DRM system can not be used at a DRM system having a different standard. Accordingly, a DRM content having been received from a DRM system having a different standard is imported to the LRM. The Imported RO may be transferred to a DRM Agent from the LRM. However, there is a technical limitation in that the DRM Agent can not transfer the Imported RO to another DRM Agent.